Method for safely disposing scrapped elemental mercury

Abstract

The invention relates to the field of hazardous waste treatment, in particular to a method for safely treating scrapped elemental mercury, which comprises the following steps: (1) oxidizing elemental mercury; (2) dissolving mercury oxide; (3) neutralization reaction; (4) mercury salt precipitation; (5) solidification and landfill of filter residues; evaporating and crystallizing filtrate to produce sodium chloride. According to the scheme, the sodium hypochlorite is used for oxidizing the mercury elementary substance to generate the basic mercuric chloride, then the basic mercuric chloride is acidified by hydrochloric acid to form the mercuric chloride solution, then sodium sulfide is added under the alkaline condition to form the mercuric sulfide precipitate, and the safe treatment of the mercury elementary substance is realized through a series of post-treatments such as solid-liquid separation and solidification. And finally, the generated filtrate is evaporated and crystallized to prepare sodium chloride, so that recycling of waste salt is realized, and zero emission of waste is realized. Compared with the prior art, the disposal method is lower in cost, and the disposal process is safer and more environmentally friendly.

Description

Technical Field

[0001] The present invention relates to the field of hazardous waste treatment, and in particular to a method for safely disposing of discarded elemental mercury. Background Art

[0002] Mercury is a liquid metal element, commonly known as quicksilver, with a melting point of -38.87°C, a boiling point of 356.6°C, and a density of 13.59 g / cm 3 Mercury is a heavy, shiny, silvery-white liquid that evaporates at room temperature. Mercury vapor and its salts (except for some with extremely low solubility, such as mercuric sulfide) are highly toxic and can cause brain and liver damage if ingested, inhaled, or contacted, making it an extremely dangerous chemical. Mercury is commonly used in the manufacture of scientific measuring instruments (such as barometers and thermometers), pharmaceuticals, catalysts, mercury vapor lamps, electrodes, fulminate of mercury, and is also used in dentistry and the cosmetics industry.

[0003] The existing methods for treating waste elemental mercury include:

[0004] The invention patent, titled "A Method for Harmless Treatment of Liquid Mercury" (publication number CN 108998691 A), utilizes the amalgam reaction between mercury and certain metals to produce a relatively stable amalgam alloy. This method uses precious metals such as gold and silver, resulting in high disposal costs. Furthermore, the process is not sealed, posing the risk of mercury volatilization.

[0005] A utility model patent, titled "A System for Treating Waste Liquid Elemental Mercury" (publication number CN 209093356 U), discloses a method for reacting silver nitrate with elemental mercury to produce stable mercuric nitrate, which is then subsequently disposed of. This solution uses expensive silver nitrate, resulting in high disposal costs. Furthermore, the mercury nitrate requires further treatment, requiring a large amount of reagents.

[0006] In order to effectively treat scrapped elemental mercury, the applicant's prior application entitled "Method for treating elemental mercury" (application number CN202311492495.X) provides a disposal method, which first uses nitric acid to dissolve elemental mercury to form mercury nitrate, and then adds sodium sulfide after alkalization to form mercury sulfide precipitate. The safe treatment of elemental mercury is achieved through solid-liquid separation, solidification and other treatments.

[0007] However, the above solution uses concentrated nitric acid to dissolve elemental mercury, which has high disposal costs and does not take into account the danger of mercury vapor volatilization. Therefore, it can be seen that the safe disposal of scrapped elemental mercury is a research topic that technicians in this field need to continuously improve. Summary of the Invention

[0008] The purpose of the present invention is to provide a method for the safe disposal of scrapped elemental mercury, so as to treat the elemental mercury safely, economically, effectively and harmlessly.

[0009] To achieve the above-mentioned purpose, the technical solution adopted by the present invention is: a method and device for the safe disposal of scrapped elemental mercury, comprising the following steps:

[0010] (1) Oxidation of elemental mercury: Sodium hypochlorite is added to the waste element to be treated to convert elemental mercury into mercury oxide;

[0011] (2) Dissolution of mercury oxide: add hydrochloric acid to dissolve the mercury oxide into mercury salt;

[0012] (3) Neutralization reaction: add alkaline reagent to adjust the pH to 8.5-9.5 to obtain a neutralized solution;

[0013] (4) Mercury salt precipitation: sodium sulfide is added to the neutralized solution, and after the reaction, solid-liquid separation is performed to obtain a filtrate and a filter residue;

[0014] (5) The filter residue is solidified and landfilled; the filtrate is evaporated and crystallized to produce sodium chloride.

[0015] The above scheme first uses sodium hypochlorite to oxidize elemental mercury to produce basic mercuric chloride, which is then acidified with hydrochloric acid to form a mercuric chloride solution. Sodium sulfide is then added under alkaline conditions to precipitate mercuric sulfide. After a series of post-treatments, including solid-liquid separation and solidification, the mercury is safely disposed of. Finally, the resulting filtrate is evaporated and crystallized to produce sodium chloride, realizing the resource utilization of waste salt and achieving zero waste discharge. Compared with existing technologies, the disposal method of this application is lower in cost, safer in process, and more environmentally friendly.

[0016] Specifically, step (1) is performed in a sealed container, and a water seal device is provided on the exhaust pipe at the top of the container to absorb the volatilized mercury vapor. The water in the water seal device that has absorbed the mercury vapor is regularly replaced and then collected and processed together in step (1). For example, the reaction container is a reactor having a feeding port and an exhaust port at the top and a discharge port at the bottom. The exhaust port and the water seal device are connected by an exhaust pipe. The mercury vapor volatilized from the scrapped elemental mercury enters the water when passing through the water seal device, and is prevented from entering the atmosphere and affecting the health of workers.

[0017] The sodium hypochlorite is a solution with a mass concentration of 5 to 15%, and the added amount is such that the mass ratio of elemental mercury to sodium hypochlorite is 1:(8.6 to 12.8).

[0018] In the step (2), hydrochloric acid is added until the pH value of the solution is ≤1. In the step (3), the alkaline reagent is a sodium hydroxide solution with a mass concentration of 20% to 30%. In the step (4), the amount of sodium sulfide added is based on the ratio of the amount of mercury ions in the neutralization solution to the amount of negative divalent sulfide ions in the sodium sulfide: Hg 2+ :S 2-=1:3~1:6. In the step (5), the solidification landfill method is: according to the mass ratio of the filter residue, cement, sand and water of 0.1:1:1.2:0.5, after mixing and stirring evenly, standing for 24 hours, curing for 7 days, and after the leaching test meets the standard, it is safely buried in a hazardous waste landfill, and finally the filtrate is evaporated and crystallized to prepare sodium chloride.

[0019] The method comprises the following steps: adding elemental mercury into a reaction kettle and using a water seal to absorb mercury vapor; adding sodium hypochlorite to oxidize the elemental mercury; fully stirring and reacting the solution, the solution turns brick red, and obtaining an elemental mercury oxide solution; adjusting the solution to be acidic (pH of about 1); stirring and reacting the solution, the solution becomes transparent and colorless; adding sodium hydroxide solution to adjust the pH of the solution to be alkaline (pH of 8.5-9.5); generating a yellow precipitate in the solution to obtain a neutralized solution; continuously adding sodium sulfide solution and fully stirring the solution to generate a black precipitate (mercuric sulfide precipitate); filtering the mixed solution containing the black mercuric sulfide to obtain a filtrate and a filter residue; the filtrate is a sodium chloride solution; evaporating and crystallizing the solution to obtain sodium chloride; and solidifying and landfilling the filter residue mercuric sulfide, thereby realizing safe disposal of the scrapped elemental mercury. DETAILED DESCRIPTION

[0020] The technical solution of the present application is further described in detail below with reference to the embodiments.

[0021] A safe disposal method for scrapped elemental mercury comprises first adding elemental mercury into a reactor and pumping water into the reactor to seal the elemental mercury. Then, 10% sodium hypochlorite and a small amount of hydrochloric acid are pumped into the reactor to oxidize the elemental mercury to prepare basic mercuric chloride. The mass ratio of elemental mercury to sodium hypochlorite is 1:8.6 to 1:12.8, and the reaction time is 12 hours. The reaction equation is as follows:

[0022] 2Hg+2NaClO+2HCl=Hg2OCl2↓+H2O+2NaCl

[0023] Furthermore, hydrochloric acid was pumped into the reactor to adjust the pH of the solution to about 1. The mass ratio of elemental mercury to hydrochloric acid was 2.10:1. The reaction was continued for 6 hours until the solution became colorless and transparent with no precipitate or undissolved elemental mercury. The reaction equation is as follows:

[0024] Hg2OCl2+2HCl=2HgCl2+H2O

[0025] After the mercury salt is completely dissolved, add a sodium hydroxide solution with a mass concentration of 20% to 30% to adjust the pH to 8.5 to 9.5, preferably 9.0. Sodium hydroxide and mercuric chloride react to form a yellow mercuric oxide precipitate. The reaction equation is as follows:

[0026] HgCl2+2NaOH==HgO↓+H2O+2NaCl

[0027] Sodium sulfide is added to the solution to react with the unreacted mercury ions, so that no mercury ions are detected in the effluent water. Sodium sulfide reacts with mercuric oxide to form mercuric sulfide. The amount of sodium sulfide added is based on a ratio of 1:3 to 1:6 based on the amount of mercury ions in the solution and the amount of negative divalent sulfide ions in the sodium sulfide. The reaction equation is as follows:

[0028] HgCl2+Na2S=HgS↓+2NaCl

[0029] HgO+Na2S+H2O=HgS↓+2NaOH

[0030] After the above reaction is completed, solid-liquid separation is carried out to obtain filter residue mercury sulfide and filtrate sodium chloride solution. The filtrate enters the evaporator for evaporation and disposal. After evaporation, sodium chloride is produced for recycling and utilization, and the filter residue is solidified and landfilled.

[0031] The solidification landfill method is: mix and stir the filter residue, cement, sand and water in a mass ratio of 0.1:1:1.2:0.5, let it stand for 24 hours, cure for 7 days, and then conduct leaching test and safely landfill it in a hazardous waste landfill after meeting the standards.

[0032] In summary, the present invention has the following beneficial effects:

[0033] First, the process flow of the present invention is simple and the operation is safe, which solves the problem of elemental mercury oxidation and improves the disposal efficiency of elemental mercury. The advantage of using sodium hypochlorite to treat elemental mercury over using nitric acid to treat elemental mercury is that it reduces the risk during the disposal process and reduces the severity of the nitric acid treatment of elemental mercury.

[0034] Secondly, the present invention uses a water seal device to absorb mercury vapor, thereby preventing elemental mercury from volatilizing into the air; the water seal device is regularly replaced with new water, and the replaced wastewater is added to the reactor for treatment together with the waste elemental mercury to be treated, thereby achieving zero wastewater discharge.

[0035] Example 1:

[0036] 2 kg of elemental mercury was added to a special elemental mercury reactor, and 2 L of water was added for water sealing. Then 17.2 kg of sodium hypochlorite and 0.36 kg of hydrochloric acid were pumped in to react for 12 hours until the solution turned brick red (the mass ratio of elemental mercury to sodium hypochlorite was 1:8.6). Then 4.2 kg of hydrochloric acid was pumped into the solution to adjust the pH of the solution to about 1. After stirring and reacting for 6 hours, the first reaction liquid was obtained. The generated acidic gas was absorbed and disposed of by the tail gas device. Then 4.8 kg of 30% liquid alkali was added to adjust the pH of the solution to 9.0. A yellow precipitate was generated in the solution to obtain the second solution. Sodium sulfide solution (the molar ratio of Hg 2+ :S 2-=1:3) and fully stirred to generate a black precipitate to obtain a third solution. The third solution was filter-filtered to obtain a filtrate and a filter residue. After the mercury content of the filtrate was tested, it was evaporated, concentrated, and crystallized to produce sodium chloride waste salt, which was collected and uniformly recycled. The distillate water was treated in a biochemical system. The filter residue was solidified and landfilled. The mixture was mixed in a ratio of filter residue: cement: sand: water = 0.1:1:1.2:0.5, stirred evenly, allowed to stand for 24 hours, and cured for 7 days. Leaching was then performed to test whether the mercury content met the landfill standard.

[0037] Example 2:

[0038] 2 kg of elemental mercury was added to a special elemental mercury reactor, and 2 L of water was added for water sealing. Then 17.2 kg of sodium hypochlorite and 0.36 kg of hydrochloric acid were pumped in to react for 12 hours until the solution turned brick red (the mass ratio of elemental mercury to sodium hypochlorite was 1:8.6). Then 4.2 kg of hydrochloric acid was pumped into the solution to adjust the pH of the solution to about 1. After stirring and reacting for 6 hours, the first reaction liquid was obtained. The generated acidic gas was absorbed and disposed of by the tail gas device. Then 4.8 kg of 30% liquid alkali was added to adjust the pH of the solution to 9.0. A yellow precipitate was generated in the solution to obtain the second solution. Sodium sulfide solution (the molar ratio of Hg 2+ :S 2- =1:5) and fully stirred to generate a black precipitate to obtain a third solution. The third solution was filter-filtered to obtain a filtrate and a filter residue. After the mercury content of the filtrate was tested, it was evaporated, concentrated, and crystallized to produce sodium chloride waste salt, which was collected and uniformly recycled. The distillate water was treated in a biochemical system. The filter residue was solidified and landfilled. The mixture was mixed in a ratio of filter residue: cement: sand: water = 0.1:1:1.2:0.5, stirred evenly, allowed to stand for 24 hours, and cured for 7 days. Leaching was then performed to test whether the mercury content met the landfill standard.

[0039] Example 3:

[0040] 2 kg of elemental mercury was added to a special elemental mercury reactor, and 2 L of water was added for water sealing. Then 17.2 kg of sodium hypochlorite and 0.36 kg of hydrochloric acid were pumped in to react for 12 hours until the solution turned brick red (the mass ratio of elemental mercury to sodium hypochlorite was 1:8.6). Then 4.2 kg of hydrochloric acid was pumped into the solution to adjust the pH of the solution to about 1. After stirring and reacting for 6 hours, the first reaction liquid was obtained. The generated acidic gas was absorbed and disposed of by the tail gas device. Then 4.8 kg of 30% liquid alkali was added to adjust the pH of the solution to 9.0. A yellow precipitate was generated in the solution to obtain the second solution. Sodium sulfide solution (the molar ratio of Hg 2+ :S 2-=1:6) and fully stirred to generate a black precipitate to obtain a third solution. The third solution was filter-filtered to obtain a filtrate and a filter residue. After the mercury content of the filtrate was tested, it was evaporated, concentrated, and crystallized to produce sodium chloride waste salt, which was collected and uniformly recycled. The distillate water was treated in a biochemical system. The filter residue was solidified and landfilled. The mixture was mixed in a ratio of filter residue: cement: sand: water = 0.1:1:1.2:0.5, stirred evenly, allowed to stand for 24 hours, and cured for 7 days. Leaching was then performed to test whether the mercury content met the landfill standard.

[0041] Example 4:

[0042] 2 kg of elemental mercury was added to a special elemental mercury reactor, and 2 L of water was added for water sealing. Then 21.6 kg of sodium hypochlorite and 0.36 kg of hydrochloric acid were pumped in to react for 12 hours until the solution turned brick red (the mass ratio of elemental mercury to sodium hypochlorite was 1:10.8). Then 4.2 kg of hydrochloric acid was pumped into the solution to adjust the pH of the solution to about 1. After stirring and reacting for 6 hours, the first reaction liquid was obtained. The generated acidic gas was absorbed and disposed of by the tail gas device. Then 4.8 kg of 30% liquid alkali was added to adjust the pH of the solution to 9.0. A yellow precipitate was generated in the solution to obtain the second solution. Sodium sulfide solution (the molar ratio of Hg 2+ :S 2- =1:3) and fully stirred to generate a black precipitate to obtain a third solution. The third solution was filter-filtered to obtain a filtrate and a filter residue. After the mercury content of the filtrate was tested, it was evaporated, concentrated, and crystallized to produce sodium chloride waste salt, which was collected and uniformly recycled. The distillate water was treated in a biochemical system. The filter residue was solidified and landfilled. The mixture was mixed in a ratio of filter residue: cement: sand: water = 0.1:1:1.2:0.5, stirred evenly, allowed to stand for 24 hours, and cured for 7 days. Leaching was then performed to test whether the mercury content met the landfill standard.

[0043] Example 5:

[0044] 2 kg of elemental mercury was added to a special elemental mercury reactor, and 2 L of water was added for water sealing. Then 21.6 kg of sodium hypochlorite and 0.36 kg of hydrochloric acid were pumped in to react for 12 hours until the solution turned brick red (the mass ratio of elemental mercury to sodium hypochlorite was 1:10.8). Then 4.2 kg of hydrochloric acid was pumped into the solution to adjust the pH of the solution to about 1. After stirring and reacting for 6 hours, the first reaction liquid was obtained. The generated acidic gas was absorbed and disposed of by the tail gas device. Then 4.8 kg of 30% liquid alkali was added to adjust the pH of the solution to 9.0. A yellow precipitate was generated in the solution to obtain the second solution. Sodium sulfide solution (the molar ratio of Hg 2+ :S 2-=1:5) and fully stirred to generate a black precipitate to obtain a third solution. The third solution was filter-filtered to obtain a filtrate and a filter residue. After the mercury content of the filtrate was tested, it was evaporated, concentrated, and crystallized to produce sodium chloride waste salt, which was collected and uniformly recycled. The distillate water was treated in a biochemical system. The filter residue was solidified and landfilled. The mixture was mixed in a ratio of filter residue: cement: sand: water = 0.1:1:1.2:0.5, stirred evenly, allowed to stand for 24 hours, and cured for 7 days. Leaching was then performed to test whether the mercury content met the landfill standard.

[0045] Example 6:

[0046] 2 kg of elemental mercury was added to a special elemental mercury reactor, and 2 L of water was added for water sealing. Then 21.6 kg of sodium hypochlorite and 0.36 kg of hydrochloric acid were pumped in to react for 12 hours until the solution turned brick red (the mass ratio of elemental mercury to sodium hypochlorite was 1:10.8). Then 4.2 kg of hydrochloric acid was pumped into the solution to adjust the pH of the solution to about 1. After stirring and reacting for 6 hours, the first reaction liquid was obtained. The generated acidic gas was absorbed and disposed of by the tail gas device. Then 4.8 kg of 30% liquid alkali was added to adjust the pH of the solution to 9.0. A yellow precipitate was generated in the solution to obtain the second solution. Sodium sulfide solution (the molar ratio of Hg 2+ :S 2- =1:6) and fully stirred to generate a black precipitate to obtain a third solution. The third solution was filter-filtered to obtain a filtrate and a filter residue. After the mercury content of the filtrate was tested, it was evaporated, concentrated, and crystallized to produce sodium chloride waste salt, which was collected and uniformly recycled. The distillate water was treated in a biochemical system. The filter residue was solidified and landfilled. The mixture was mixed in a ratio of filter residue: cement: sand: water = 0.1:1:1.2:0.5, stirred evenly, allowed to stand for 24 hours, and cured for 7 days. Leaching was then performed to test whether the mercury content met the landfill standard.

[0047] Example 7:

[0048] 2 kg of elemental mercury was added to a special elemental mercury reactor, and 2 L of water was added for water sealing. Then 25.6 kg of sodium hypochlorite and 0.36 kg of hydrochloric acid were pumped in to react for 12 hours until the solution turned brick red (the mass ratio of elemental mercury to sodium hypochlorite was 1:12.8). Then 4.2 kg of hydrochloric acid was pumped into the solution to adjust the pH of the solution to about 1. After stirring and reacting for 6 hours, the first reaction liquid was obtained. The generated acidic gas was absorbed and disposed of by the tail gas device. Then 4.8 kg of 30% liquid alkali was added to adjust the pH of the solution to 9.0. A yellow precipitate was generated in the solution to obtain the second solution. Sodium sulfide solution (the molar ratio of Hg 2+ :S 2-=1:3) and fully stirred to generate a black precipitate to obtain a third solution. The third solution was filter-filtered to obtain a filtrate and a filter residue. After the mercury content of the filtrate was tested, it was evaporated, concentrated, and crystallized to produce sodium chloride waste salt, which was collected and uniformly recycled. The distillate water was treated in a biochemical system. The filter residue was solidified and landfilled. The mixture was mixed in a ratio of filter residue: cement: sand: water = 0.1:1:1.2:0.5, stirred evenly, allowed to stand for 24 hours, and cured for 7 days. Leaching was then performed to test whether the mercury content met the landfill standard.

[0049] Example 8:

[0050] 2 kg of elemental mercury was added to a special elemental mercury reactor, and 2 L of water was added for water sealing. Then 25.6 kg of sodium hypochlorite and 0.36 kg of hydrochloric acid were pumped in to react for 12 hours until the solution turned brick red (the mass ratio of elemental mercury to sodium hypochlorite was 1:12.8). Then 4.2 kg of hydrochloric acid was pumped into the solution to adjust the pH of the solution to about 1. After stirring and reacting for 6 hours, the first reaction liquid was obtained. The generated acidic gas was absorbed and disposed of by the tail gas device. Then 4.8 kg of 30% liquid alkali was added to adjust the pH of the solution to 9.0. A yellow precipitate was generated in the solution to obtain the second solution. Sodium sulfide solution (the molar ratio of Hg 2+ :S 2- =1:5) and fully stirred to generate a black precipitate to obtain a third solution. The third solution was filter-filtered to obtain a filtrate and a filter residue. After the mercury content of the filtrate was tested, it was evaporated, concentrated, and crystallized to produce sodium chloride waste salt, which was collected and uniformly recycled. The distillate water was treated in a biochemical system. The filter residue was solidified and landfilled. The mixture was mixed in a ratio of filter residue: cement: sand: water = 0.1:1:1.2:0.5, stirred evenly, allowed to stand for 24 hours, and cured for 7 days. Leaching was then performed to test whether the mercury content met the landfill standard.

[0051] Example 9:

[0052] 2 kg of elemental mercury was added to a special elemental mercury reactor, and 2 L of water was added for water sealing. Then 25.6 kg of sodium hypochlorite and 0.36 kg of hydrochloric acid were pumped in to react for 12 hours until the solution turned brick red (the mass ratio of elemental mercury to sodium hypochlorite was 1:12.8). Then 4.2 kg of hydrochloric acid was pumped into the solution to adjust the pH of the solution to about 1. After stirring and reacting for 6 hours, the first reaction liquid was obtained. The generated acidic gas was absorbed and disposed of by the tail gas device. Then 4.8 kg of 30% liquid alkali was added to adjust the pH of the solution to 9.0. A yellow precipitate was generated in the solution to obtain the second solution. Sodium sulfide solution (the molar ratio of Hg 2+ :S 2-=1:6) and fully stirred to generate a black precipitate to obtain a third solution. The third solution was filter-filtered to obtain a filtrate and a filter residue. After the mercury content of the filtrate was tested, it was evaporated, concentrated, and crystallized to produce sodium chloride waste salt, which was collected and uniformly recycled. The distillate water was treated in a biochemical system. The filter residue was solidified and landfilled. The mixture was mixed in a ratio of filter residue: cement: sand: water = 0.1:1:1.2:0.5, stirred evenly, allowed to stand for 24 hours, and cured for 7 days. Leaching was then performed to test whether the mercury content met the landfill standard.

[0053] Solidification test results: After testing, no mercury was detected in the filtrate and the leachate of the filter residue solidification in the above Examples 1-9. It can be seen that the above solution is not only low-cost, but also improves the disposal efficiency and completely realizes the safe disposal of elemental mercury.

[0054] Water seal effect test: The content of elemental mercury volatilized in the tail gas during the present application (using a water seal device) and the treatment of elemental mercury with nitric acid is compared in Table 1:

[0055] Table 1 Mercury vapor content detection before and after water sealing

[0056] <![CDATA[Volatile elemental mercury content (mg / m 3 )]]> Water seal device outlet gas sampling 0.01 Water seal device intake air sampling 2.5

[0057] By comparison, it can be seen that the solution of setting up a water seal device in this application greatly reduces the mercury vapor content in the exhaust gas, and the water seal device only needs to immerse the exhaust pipe mouth in water. It has a simple structure, low cost, good effect, and is environmentally friendly.

Claims

1. A method for the safe disposal of waste elemental mercury, comprising the following steps: (1) Oxidation of elemental mercury: Sodium hypochlorite is added to the waste element to be treated to convert elemental mercury into mercury oxide; (2) Dissolution of mercury oxide: add hydrochloric acid to dissolve the mercury oxide into mercury salt; (3) Neutralization reaction: add alkaline reagent to adjust the pH to 8.5-9.5 to obtain a neutralized solution; (4) Mercury salt precipitation: sodium sulfide is added to the neutralized solution, and after the reaction, solid-liquid separation is performed to obtain a filtrate and a filter residue; (5) The filter residue is solidified and landfilled; the filtrate is evaporated and crystallized to produce sodium chloride.

2. The method for safe disposal of waste elemental mercury according to claim 1, characterized in that: The step (1) is carried out in a sealed container, and a water seal device is provided on the exhaust pipe at the upper part of the container. The water in the water seal device that has absorbed mercury vapor is replaced regularly and then collected into the step (1) for treatment.

3. The method for safe disposal of waste elemental mercury according to claim 1, characterized in that: In the step (1), sodium hypochlorite is a solution with a mass concentration of 5 to 15%, and the added amount: the mass ratio of elemental mercury to sodium hypochlorite is 1:(8.6 to 12.8).

4. The method for safe disposal of waste elemental mercury according to claim 1, characterized in that: In the step (2), hydrochloric acid is added until the pH value of the solution is ≤1.

5. The method for safe disposal of waste elemental mercury according to claim 1, characterized in that: In the step (3), the alkaline reagent is a sodium hydroxide solution with a mass concentration of 20% to 30%.

6. The method for safe disposal of waste elemental mercury according to claim 1, characterized in that: In the step (4), the amount of sodium sulfide added is based on the ratio of the amount of mercury ions in the neutralization solution to the amount of negative divalent sulfide ions in the sodium sulfide: Hg 2+ :S 2- =1:3~1:

6.

7. The method for safe disposal of waste elemental mercury according to claim 1, characterized in that: In the step (5), the solidification landfill method is: according to the mass ratio of the filter residue, cement, sand and water of 0.1:1:1.2:0.5, the mixture is mixed and stirred evenly, and then allowed to stand for 24 hours, cured for 7 days, and the mixture is safely landfilled in a hazardous waste landfill after the leaching test meets the standards.